The heat is on

23 May 2015

The heat is on
With the increasing demands for fast production and top quality, packaging converters are having to make important decision regarding the technologies they use. Converting Today investigates the benefits and advantages of the array of techniques available to them.

The heat is on

With the increasing demands for fast production and top quality, packaging converters are having to make important decision regarding the technologies they use. Converting Today investigates the benefits and advantages of the array of techniques available to them.

It comes as no surprise that packaging converters are under mounting pressure from their clients to produce work that meets an increasing number of requirements. Short turnaround times, high print quality and strong durability are only some of the values the end products are expected to have. This is all well and good, but when a job is "needed yesterday" without any compromise on quality, converters are required to use to the technology available to them to meet these goals.
While drying and curing technology offers established means of increasing a product's speed to market, there are a number of methods to employ that will, in turn, offer different benefits and advantages to their users.
Pressure-sensitive adhesive (PSA) coating is common for tapes and labels, and is useful for many market applications. This is a broad area that has many caveats, with the range of coating chemically spanning low solids content within a solvent to 100% solids hot-melt adhesive coating. With these changing chemistries come many decisions, from pump type to substrate interaction energy to coating head system.
When deciding on coating methods for PSA chemistry, there are various options, but one element to consider is the adhesive formulation. To reduce the use of curing energy and to speed up the process, reducing solvent content can provide advantages.
According to Mark Miller, a fluid coating expert who runs Coating Tech Service LLC, as well as being a regular contributor to Paper Film and Foil Converter, the curing step in coating is typically the bottleneck. "Whether it is oven curing or drying, UV curing or eBeam, the technology takes some time based on the interaction with the chemistry. Understanding whether solvents are simply being dried off, or whether the adhesive is reacting to form a complex molecule, will dictate the limits of the curing process and subsequently the line speeds."
He continues: "While many coating techniques require a specific viscosity range to coat successfully, there are technologies that can successfully coat viscosities from 1 to 100,000cP or more. These coating systems allow maximum flexibility in formulation development and the possibility of reduced energy use and maximum line speed. In a return on investment calculation for coating system technology, this should be a consideration. While there will be time associated with re-formulation by chemists and product development engineers, the savings may be more than covered in the increased line speeds of the production process."

UV growth
While ultra-violet curing is used in a raft of applications, such as the flexographic package printing of folding cartons, this has been mainly confined to the role of varnishing. Now, an increasing number of press manufacturers are adopting UV curing for a wider gamut of package printing, ranging from cartons to labels and other flexible packaging materials. With more than 2,000 label presses currently using UV curing, it is clear that we're looking at a burgeoning market.
UV and electron-beam (EB) curing offer a number of advantages for packaging converters. The immediate curing of inks, varnishes and coatings, in turn, enables the operator to progress with other finishing processes without a costly drying period.
Another benefit of instant curing in this context is the impact it has on preventing the growth of ink dots on the substrate. Curing ensures that the print remains sharp and bright, especially when the substrate being used has absorbing qualities.


Recent installation
Specialist flexible label printer Coveris has upgraded its Mark Andy 4150 flexo press with an energy-efficient GEW UV curing system. Coveris made the investment to support its effort in optimising reliability of production output, increasing uptime and reducing energy consumption.
David Dickinson, group engineer with Coveris, commented: "With the running cost we had for spare parts and energy, we had come to a point where it was no longer viable to run the old system. We made the decision to upgrade to an alternative, and GEW's Rhino came out on top."
Roly Banks, site manager at Coveris' Cramlington plant, added: "We are no longer losing production due to component failure. The new system has improved our productivity massively. The thing we are most comfortable with now is that, in the nine months we have run Rhino here, the system has been 100% reliable. We've had no failures." In addition, the lower temperature of the GEW system means less heat and CO2 discharge.

In Their Words - advantages of UV/EB curing
Converting Today spoke with a number of inks executives to understand more about the advantages they are seeing in energy curing, such as performance, production or regulatory benefits, and how it can drive new business.
"There are a number of advantages, including immediate handling, textured affects, nearly VOC-free emissions and various specialty applications,"?explained John Copeland, president and COO of ToyoInk America. "We have seen significant growth in the UV market over the past few years, with no sign of anything slowing down, and the strongest growth in high-end commercial, label and packaging."
"Key advantages are solvent-free, resulting in lower insurance, a high level of product resistance, ease of use, and flexibility to accommodate various sizes and a variety of print jobs,"?adds Brij Nigram, VP IdeOn LLC, a printing solutions consulting company. "Industrial applications, label and some flexible packaging continue to be the primary growth areas, which is why our focus is to develop new curing printing technologies that could be used in a wide applications for flexible packaging," he says.
"The advantages of energy-curable technologies include quick turnaround, durability, low energy consumption and enhanced visual effects on specialty coatings,"?says Beau Snider, field manager - corporate technical services at Wikoff Color. "Also, EB technology allows food packaging printers to have a significant technological advantage because of its high level of curing."
Tony Renzi, VP product management Liquid Inks, North America, concluded: "UV/EB printing and coating can reduce total production costs by instant drying through the curing process, allowing additional processing and finishing immediately and, in many cases, in line with the printing process.
"UV inks also give our customers another way to be eco-efficient, and deliver economically competitive goods and services that satisfy their customers' needs and bring quality of life, while progressively reducing their ecological impact and resource intensity throughout the life-cycle. The UV inks allow customers to conserve energy in their printing process and use products that are manufactured with little or no volatile organic compounds."

Electron Beam

EB curing is another process that can cure thick films, even when working with opaque surfaces. This makes it ideal for curing adhesives that are used in lamination. It is capable of drying all colours at the same speed, polymerising the ink in the process.
"The full range of printing technologies are today employing energy curing of their inks," says David Helsby, president of RadTech Europe, the association that promotes UV and EB curing. "The key drivers are packaging innovations, such as the shift from rigid to flexible materials; faster high-volume print without reduced quality; brand-owners' requirements for just-in-time delivery; and the need to reduce overall packaging costs today.
"However, unlike many drying methods, EB generates very little heat and works well with specific chemistries, but the key drawback is that it's an expensive process. Capital investment costs are considered high, and recouping that expense is probably beyond the average packaging converter.
"A vacuum chamber is needed," adds Helsby, "as is the high voltage power supply and the need to create an inert atmosphere. Because of the unsurpassed characteristics of the resulting coating and the environmentally friendly aspects, issues such as energy consumption and avoiding waste water and waste gases will become increasingly important in the future."

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